JPH09306000A - Biaxial actuator and optical disc apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a biaxial actuator and an optical disc apparatus which have improved vibration-resistant properties. SOLUTION: A dual-axis actuator 15 has a lens holder which supports an object lens, elastic supporting members 15a with which the lens holder is supported by fixed part so as to be able to move at least in the direction of the optical axis of the object lens, a driving means by which the lens holder is moved reatively to the fixed part and a mechanical deck to which the fixed part is fixed and which is attached to the frame of an optical pickup, etc., with an insulator 12 therebetween. The biaxial actuator 15 is so constructed as to have its resonance frequency F0 higher than the resonance frequency f0 of the mechanical deck.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a biaxial actuator for recording and / or reproducing information on an optical disc such as a compact disc (CD), a CD-ROM and a magneto-optical disc (MO), and an optical disc device. .

[0002]

2. Description of the Related Art Conventionally, reproduction or recording of an information signal on an optical disc, for example, a so-called compact disc (CD) or a magneto-optical disc is performed by using an optical pickup. This optical pickup includes a semiconductor laser as a light source, an objective lens, an optical system, and a photodetector.

In an optical pickup, a light beam emitted from a semiconductor laser is focused on a recording surface of an optical disc by an objective lens via an optical system. The return light beam from the optical disc is separated from the light beam emitted from the semiconductor laser by the optical system and guided to the photodetector. The light beam emitted from the semiconductor laser follows the displacement of the optical disc in the direction orthogonal to the surface direction of the optical disc caused by the warp of the optical disc, etc., and is focused on the recording surface of the optical disc. The position of the objective lens in the optical axis direction is adjusted. At the same time, the position in the direction perpendicular to the optical axis of the objective lens is adjusted so that the position of the spot on the optical disk of the light beam emitted from the semiconductor laser follows the eccentricity of the optical disk or the meandering of the track formed on the optical disk. Is done.

The focus position of the light beam emitted from the semiconductor laser and the spot position on the recording surface of the optical disc are adjusted by adjusting the objective lens in the optical axis direction of the objective lens and in the direction orthogonal to the optical axis. It is done by adjusting. An electromagnetically driven actuator is used to adjust the position of the objective lens. This actuator is called an objective lens actuator or a biaxial actuator, and includes a bobbin to which an objective lens is attached, a plurality of elastic support members, and a driving unit that generates a driving force.
The bobbin is supported by a plurality of elastic supporting members with respect to the fixed portion such that the position in the optical axis direction of the objective lens, that is, the focus position and the position in the direction orthogonal to the optical axis of the objective lens, that is, the tracking position, are adjustable. ing. An optical disk device including such a biaxial actuator and an optical pickup is configured as shown in FIG.

In FIG. 7, an optical disk device 1 includes a frame 2, a mechanical deck 4 instructed on the frame 2 through an insulator 3, an optical pickup 5 mounted on the mechanical deck 4, and a built-in optical pickup 5. Biaxial actuator 6 for supporting a fixed objective lens
It is composed of

The mechanical deck 4 has a so-called floating structure for vibration resistance by being supported by the insulator 3 with respect to the frame 2 of the optical disk device 1. As a result, the mechanical deck 4 has a unique resonance frequency f0 of the insulator 3 with respect to the frame 2, as shown in FIG.

The optical pickup 5 includes a light source and a photodetector, and a light beam from the light source passes through an objective lens (not shown) supported by a biaxial actuator 6 and a signal recording surface of an optical disc. Then, the light beam returned from the optical disc is incident on the photodetector again through the objective lens, and the information recorded on the signal recording surface of the optical disc is reproduced based on the output signal of the photodetector. It

The lens holder of the biaxial actuator 6 is movable by the elastic support member 6a in two directions perpendicular to the fixed portion attached to the optical pickup 5, that is, the code tracking direction and the focusing direction. It is supported.

Further, the lens holder of the biaxial actuator 6 is provided with a focusing coil and a tracking coil (not shown). By energizing the focusing coil and the tracking coil, the magnetic flux generated in each coil interacts with the magnetic flux generated by the yoke attached to the fixed portion and the magnet (not shown) attached to the fixed portion. The objective lens supported by the lens holder is appropriately moved in the focusing direction and the tracking direction.

In the biaxial actuator 6 having such a structure, the lens holder having the objective lens and the coil is connected to the fixed portion, the optical pickup 5, and the mechanical deck 4 by the elastic supporting member 6a as a movable portion. Therefore, as shown in FIG. 9, it has an inherent resonance frequency F0.

[0011]

However, in the biaxial actuator 6 having such a configuration, the resonance frequency F0 of the movable portion of the biaxial actuator 6 described above is generally the resonance frequency f0 of the mechanical deck 4 described above. Is often about the same as or lower than. Further, the vibration characteristics of the biaxial actuator 6 and the mechanical deck 4 are both shown in FIG.
And as shown in FIG. 9, at frequencies lower than the resonance frequencies f0 and F0, although it is somewhat difficult to move, it is almost constant, whereas at frequencies higher than the resonance frequency, for example, −12 dB / Decrease in oct and become difficult to move.

Here, when the resonance frequency F0 of the biaxial actuator 6 is almost the same as the resonance frequency f0 of the mechanical deck 4, the resonance frequency of the entire optical disk device 1 is
The combination of these resonance frequencies f0 and F0 gives
As shown in 0, the amplitude becomes relatively large at the resonance frequency f0 (= F0). On the other hand, when the resonance frequency F0 of the biaxial actuator 6 is lower than the resonance frequency f0 of the mechanical deck 4, the resonance frequency of the entire optical disk device 1 is shown in FIG. 11 by the combination of these resonance frequencies f0 and F0. As shown, the amplitude at the resonance frequency F0 becomes relatively large.

Further, the movable portion of the biaxial actuator 6 supported by the elastic support member 6a is moved even from the just focus position to the focus direction so that the movement of the focus direction by the focus servo can be easily controlled. The low-frequency resonance frequency is constructed so as not to change so much, but in this case, on the contrary, there was a problem in terms of vibration resistance.

Furthermore, in the state where the driving voltage is not applied to the focusing coil, the biaxial actuator 6 is used.
The movable part hangs downward due to its own weight against the tension of the elastic support member 6a. For this reason,
When the fixed portion of the biaxial actuator 6 is attached to the optical pickup 5, after the fixed portion is first bonded to the optical pickup 5, the focusing coil is energized to set the objective lens 2a to the just focus position. It Therefore, in order to raise the objective lens to the just focus position, electric power is required and the movable center of the movable portion is displaced downward.
When vibration is applied from the outside, the movable portion easily hits the lower stopper, so that there is a problem that correct focusing cannot be performed during recording / reproduction of the optical disc.

In view of the above points, it is an object of the present invention to provide a biaxial actuator and an optical disk device having improved vibration resistance.

[0016]

According to the present invention, there is provided a lens holder for supporting an objective lens, and the lens holder is movable with respect to a fixed portion at least along the optical axis direction of the objective lens. An elastic support member for supporting,
A biaxial actuator including drive means for moving the lens holder with respect to a fixed portion, and a mechanical deck to which the fixed portion is fixed and which is attached to a frame or the like of an optical pickup via an insulator. In the above, it is achieved by a biaxial actuator characterized in that the resonance frequency of the biaxial actuator is set higher than the resonance frequency of the mechanical deck.

Further, according to the present invention, the above-mentioned object is to irradiate light to the rotating optical disk through the objective lens to the rotational driving means for rotationally driving the optical disk, and to return light from the signal recording surface of the optical disk. An optical pickup that detects the light with a photodetector through an objective lens, and a biaxial actuator that movably supports the objective lens in two axial directions,
A signal processing circuit for generating a reproduction signal based on a detection signal from the photodetector, and a servo circuit for moving the objective lens of the optical pickup in two axial directions based on the detection signal from the photodetector, The biaxial actuator is
A lens holder that supports the objective lens, an elastic support member that movably supports the lens holder with respect to the fixed portion along at least the optical axis direction of the objective lens, and a drive that moves the lens holder with respect to the fixed portion. Means and
In the optical disk device, wherein the fixing portion is fixed, and a mechanical deck that is attached to the frame of the optical pickup via an insulator, the resonance frequency of the biaxial actuator is higher than the resonance frequency of the mechanical deck. It is also achieved by an optical disc device characterized in that

According to the above construction, the resonance frequency of the biaxial actuator is set higher than the resonance frequency of the mechanical deck, so that the resonance frequency of the biaxial actuator, which is relatively large in motion, is reduced in the vibration region of the mechanical deck. It will fit inside. Therefore, the vibration characteristic as a whole becomes gentle and is relatively reduced, so that the vibration resistance of the biaxial actuator is improved.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to FIGS.
Note that the embodiments described below are preferred specific examples of the present invention, and therefore, various technically preferable limitations are added. However, the scope of the present invention particularly limits the present invention in the following description. It is not limited to these embodiments unless otherwise stated.

FIG. 1 shows an optical disk device incorporating an embodiment of a biaxial actuator according to the present invention. In FIG. 1, the optical disk device 10 includes a frame 1
1, a mechanical deck 13 instructed on the frame 11 via an insulator 12, an optical pickup 14 mounted on the mechanical deck 13, and an optical pickup 1
And a biaxial actuator 15 that supports the objective lens incorporated in the optical axis 4.

The mechanical deck 13 has a so-called floating structure for vibration resistance by being supported by the insulator 12 with respect to the frame 11 of the optical disk device 10. As a result, the mechanical deck 13 is, with respect to the frame 11, similar to the insulator 3 in FIG.
Will have.

The optical pickup 14 includes a light source and a photodetector, and a light beam from the light source passes through an objective lens (not shown) supported by a biaxial actuator 15 and a signal recording surface of an optical disc. Then, the light beam returned from the optical disc is incident on the photodetector again through the objective lens, and the information recorded on the signal recording surface of the optical disc is reproduced based on the output signal of the photodetector. It

The lens holder of the biaxial actuator 15 is movable by the elastic support member 15a in two directions perpendicular to the fixed portion attached to the optical pickup 14, that is, the code tracking direction and the focusing direction. It is supported.

The lens holder of the biaxial actuator 15 is provided with a focusing coil and a tracking coil (not shown). By energizing the focusing coil and the tracking coil, the magnetic flux generated in each coil interacts with the magnetic flux generated by the yoke attached to the fixed portion and the magnet (not shown) attached to the fixed portion. The objective lens supported by the lens holder is appropriately moved in the focusing direction and the tracking direction.

The biaxial actuator 15 having such a structure
9, since the lens holder including the objective lens and the coil is connected to the fixed portion, the optical pickup 14 and the mechanical deck 13 by the elastic supporting member 15a as the movable portion, the two-axis actuator 6 in FIG. Similarly, it will have its own resonant frequency F0.

The above-mentioned structure is similar to that of the conventional optical disk device 1 shown in FIG. 7, but in the optical disk device 10 having the biaxial actuator 15 according to the embodiment of the present invention, the above-mentioned biaxial device is used. The resonance frequency F0 of the actuator 15 is set to be higher than the resonance frequency f0 of the mechanical deck 13. Here, for example, when the elastic support member 15a is a parallel link leaf spring, the resonance frequency F0 can be easily set low by changing the thickness of the portion of the leaf spring that is deformed during focusing.

Further, as shown in FIG. 3, the biaxial actuator 15 is movable at a position where the movable portion 15b including the lens holder and the coil hangs down due to its own weight against the tension of the elastic supporting member 15a. The objective lens 16 is supported by the portion 15b so as to be at a just focus position, that is, the optical beam irradiated onto the optical disc 17 by the objective lens 16 is imaged on the signal recording surface of the optical disc 17. . As a result, the objective lens 16 is located at the just focus position in a state where the driving means in the focusing direction is not energized, and the upper stroke and the lower stroke with respect to the upper and lower stoppers (not shown) in the focusing direction. The amount is almost the same.

Further, the thickness of the elastic support member 15a in the focus direction is compared with the thickness L1 at the tip of the movable portion and the thickness L2 at the fixed portion side as shown in FIG. It is formed to be thicker.

The optical disk device 10 and the biaxial actuator 15 according to the embodiment of the present invention are configured as described above, and the focus servo signal and the tracking servo signal are supplied to the focusing coil and the tracking coil provided in the movable portion. A drive current based on the tracking servo signal is supplied to each. As a result, the biaxial actuator 15 is driven by the DC magnetic field of the magnetic circuit and the magnetic fields generated by the focusing coil and the tracking coil.
The lens holder, that is, the objective lens 16 is driven in the focus direction and the tracking direction.

Here, as shown in FIG. 2, the resonance frequency F0 of the biaxial actuator is set higher than the resonance frequency f0 of the mechanical deck 13. Therefore, the resonance frequency F0 of the biaxial actuator, in which the movement is relatively large, is, for example, −12 dB / oct in the vibration characteristic of the mechanical deck.
It will fall within the attenuation range that is attenuated by. As a result, the overall vibration characteristics of the optical disk device 10 are moderated and relatively reduced.
The vibration level transmitted to the biaxial actuator is relatively low, and the vibration resistance of the biaxial actuator 15 is improved.

As a result, a reproduction defect such as a skipped sound which occurs when an external vibration is applied during reproduction of the optical disk is eliminated, and stable recording or reproduction of the optical disk becomes possible. .

When vibration is applied to the optical disk device 10 from the outside, the movable part of the biaxial actuator 15 has the same amount of stroke in the vertical direction with respect to the focus direction, so that the stopper is carelessly taken. When hitting
Focusing is not hindered, and recording or reproduction of the optical disc 17 is reliably performed. The movable part of the biaxial actuator 15 and the objective lens 16
Is in the just focus position without energizing the focusing coil, it is not necessary to energize the focusing coil in order to hold the objective lens 16 at the just focus position, and power consumption is reduced.

Further, since the elastic supporting member 15a for supporting the movable portion of the biaxial actuator 15 is formed as shown in FIGS. 4 and 5, the movable portion moves slightly from the just focus position in the focusing direction. In this case, the movable portion moves by deforming the vicinity of the tip of the elastic support member 15a, which has a relatively small thickness. Therefore, the restoring force is relatively small. On the other hand, when the movable portion largely moves from the just focus position in the focusing direction, the elastic support member 15a is deformed over the entire surface, whereby the movable portion moves. Therefore, the restoring force becomes relatively large. Thus, even when the biaxial actuator 15 moves relatively far from the just focus position, the vibration resistance is improved.

FIG. 6 shows an embodiment in which the present invention is applied to a so-called shaft sliding type biaxial actuator. In FIG. 6, the biaxial actuator 20 is the optical disc 2
1. A lens holder 23 supported so as to be movable in the axial direction and rotatable about the shaft with respect to a support shaft 22 extending perpendicularly to the signal recording surface of the first lens, and eccentric from the support shaft of the lens holder 23. The objective lens 24, whose optical axis is held in parallel with the support shaft at the above position, and the base 26 to which the support shaft 22 is attached and the lens holder 23 is connected via the damper 25. The base 26 is fixedly held on a mechanical deck connected to a frame or the like via an insulator by an optical disk device (not shown). Furthermore, the biaxial actuator 2
Reference numeral 0 indicates that a focusing coil (not shown) is wound around the cylindrical outer peripheral surface of the lens holder 23, and a pair of tracking coils (not shown) are provided on opposite sides of the outer surface of the focusing coil. Is attached. On the other hand, on the base 26, a pair of yokes made of a magnetic material is arranged so as to face the focusing coil and the tracking coil.

The above-mentioned structure is the same as that of the conventionally known shaft sliding type biaxial actuator, but in the biaxial actuator 20 of the embodiment of the present invention shown in FIG. 6, the movable part of the biaxial actuator 20 is changed. Lens holder 2
Since the lens holder 23 is coupled to the base 26 via the damper 25, the resonance frequency F0 of 3 is
It is set higher than the resonance frequency f0 of the mechanical deck of the optical disk device.

The biaxial actuator 20 having such a configuration
According to the above, similarly to the biaxial actuator 15 in the optical disk device 10 shown in FIG. 1, the vibration characteristics of the optical disk device become gentle as a whole, are relatively reduced, and are transmitted to the biaxial actuator. Is relatively low, and the vibration resistance of the biaxial actuator 20 is improved.

In the above-described embodiment, the elastic support member 15a has one end fixed to the lens holder of the biaxial actuator 15 and the other end fixed to the fixing portion, for example, a leaf spring. Although it is formed in the shape of a wire, it is not limited to this, and it is obvious that it may be formed in the shape of a wire or another shape.

[0038]

As described above, according to the present invention, it is possible to provide a biaxial actuator and an optical disk device having improved vibration resistance.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a configuration of an optical disk device incorporating a first embodiment of a biaxial actuator according to the present invention.

FIG. 2 is a graph showing vibration characteristics in the optical disk device of FIG.

FIG. 3 is a schematic side view showing a stroke of a movable portion of a biaxial actuator in the optical disc device of FIG.

4 is an enlarged side view of a biaxial actuator in the optical disc device of FIG.

5 is a schematic perspective view showing an elastic support member in the biaxial actuator of FIG.

FIG. 6 is a schematic side view showing a second embodiment of a biaxial actuator according to the present invention.

FIG. 7 is a schematic diagram showing a configuration of an example of an optical disc device including a conventional biaxial actuator.

8 is a graph showing vibration characteristics of a mechanical deck in the optical disc device of FIG.

9 is a graph showing vibration characteristics of a biaxial actuator in the optical disc device of FIG.

10 is a graph showing an example (F0 = f0) of combined vibration characteristics in the optical disk device of FIG.

11 is a graph showing another example (F0 <f0) of combined vibration characteristics in the optical disk device of FIG.

[Explanation of symbols]

10 ... Optical disk device, 11 ... Frame, 12
... Insulator, 13 ... Mechanical deck, 14 ...
..Optical pickup, 15 ... Biaxial actuator, 15a ... Elastic support member, 15b ... Movable part,
16 ... Objective lens, 17 ... Optical disk, 20 ...
..Biaxial actuators, 21 ... Optical disks, 22
... Support shaft, 23 ... Lens holder, 24 ...
Objective lens, 25 ... Damper, 26 ... Base.

Claims (5)

[Claims] 1. A lens holder for supporting an objective lens, an elastic support member for movably supporting the lens holder with respect to a fixed portion along at least an optical axis direction of the objective lens, and the lens holder for the fixed portion. A biaxial actuator, comprising: a driving means for moving the biaxial actuator relative to each other; and a mechanical deck to which the fixing portion is fixed and which is attached to a frame or the like of an optical pickup via an insulator. A biaxial actuator, wherein a resonance frequency is set higher than a resonance frequency of the mechanical deck. 2. The lens holder is arranged so as to achieve a just focus at a position where the lens holder hangs down by its own weight against the tension of the elastic support member when the drive means is not driven (when no power is supplied). The biaxial actuator according to claim 1, wherein 3. The low-range resonance frequency of a movable portion including the lens holder and the objective lens is configured to become higher as it moves away from the just focus position in the focus direction. Biaxial actuator. 4. The biaxial according to claim 2, wherein the stroke of the lens holder in the focus direction is set to be the same amount from the just focus position to one and the other in the optical axis direction. Actuator. 5. A rotation driving means for driving the optical disc to rotate, and a rotating optical disc is irradiated with light through an objective lens, and return light from a signal recording surface of the optical disc is detected by a photodetector through the objective lens. An optical pickup for detection, a biaxial actuator that supports the objective lens so that it can move in two axial directions, a signal processing circuit that generates a reproduction signal based on the detection signal from the photodetector, and detection from the photodetector. A servo circuit for moving the objective lens of the optical pickup in biaxial directions based on the signal, wherein the biaxial actuator supports the objective lens, and at least the objective lens with respect to the fixed part. Elastic supporting member for movably supporting the optical axis of the lens, and driving means for moving the lens holder with respect to the fixed portion. In the optical disc device, wherein the fixing portion is fixed and a mechanical deck that is attached to the frame of the optical pickup via an insulator is used, the resonance frequency of the biaxial actuator is the resonance frequency of the mechanical deck. An optical disk device characterized by being set higher than the above.